1. Technical Field
The present invention relates to an optical module including an interference filter that extracts light of a prescribed wavelength from an incident light and a spectroscopic analyzer including the optical module.
2. Related Art
In the related art, an interference filter (etalon) in which multi-layer films (reflecting films) are disposed on the facing surfaces of a pair of substrates so as to face each other with a prescribed gap therebetween is known (for example, see JP-A-11-142752).
In the interference filter disclosed in JP-A-11-142752, driving electrodes are disposed on the facing surfaces of the pair of reflecting films so as to face each other in order to adjust the gap, and the gap can be adjusted by an electrostatic attractive force by applying a driving voltage to the respective driving electrodes. In this way, the interference filter can pass only light of a specific wavelength corresponding to the gap. That is, the interference filter causes the incident light to experience multiple interference between the pair of reflecting films and passes only light of the specific wavelength which is strengthened by the multiple interference.
However, the above-described interference filter is generally used by being incorporated into an optical module or a spectroscopic analyzer. FIG. 13 is a schematic view showing a simplified configuration of a colorimetric device 10 (spectroscopic analyzer) of the related art including an etalon 50.
The colorimetric device 10 includes a light source device 20 that emits light to a test subject A, the etalon 50 that disperses a test subject light reflected by the test subject A, a light receiving element 420 that receives light having passed through the etalon 50, and a colorimetric sensor 40 (optical module) including an outer housing 40A in which a printed substrate 410 connected to the light source device 20 and the light receiving element 420 is accommodated.
The colorimetric sensor 40 includes a cylindrical holding housing 310 that is provided adjacent to the light source device 20 so as to hold the outer circumference of the etalon 50.
Moreover, in the colorimetric device 10, light emitted from the light source device 20 is reflected by the test subject A, and the reflected test subject light is dispersed by the colorimetric sensor 40. Based on a detection signal output from the colorimetric sensor 40, the chromaticity of the test subject light, namely the color of the test subject A is analyzed and measured from the intensities of light of the dispersed respective wavelengths.
However, in the configuration of the related art shown in FIG. 13, the holding housing 310 holds the outer circumference adjacent to a portion of the etalon 50 in which the reflecting film is formed. In such a configuration, heat generated by the light source device 20 may be transmitted directly to the etalon 50 from the holding housing 310. Thus, the substrate may be deformed by thermal expansion.
In addition, since the outer circumference of the etalon 50 adjacent to the reflecting film is held by the holding housing 310, the substrate may be deformed by the holding force of the holding housing 310.
As above, when the reflecting film is deformed, there is a problem in that the transmission wavelength of light passing through the etalon 50 may fluctuate, and the resolution may decrease.